1. Field of the Invention
The present invention relates to a novel azolinyl acetic acid derivative and a recording material using as coupling component a combination of at least one azolinyl acetic acid derivative and a diazo compound. In particular, the invention is concerned with a thermal recording material which has excellent storability before images are recorded thereon (unprocessed stock storability) and high color formation efficiency, is reduced in coloration of a background portion due to exposure to light, and ensures high image stability (light fastness) in a recorded portion.
2. Description of the Related Art
Diazo compounds form azo dyes by reacting with compounds referred to as “couplers”, such as phenol derivatives and compounds having active methylene groups. In addition, the diazo compounds have the property of decomposing when irradiated with light and losing their activities. This property of diazo compounds has been long exploited for photo recording materials, typified by diazo copy, as described in a book entitled “Shashin Kogaku no Kiso—Higin-en Shashin Hen—” (“Fundamentals of Photographic Engineering—Nonsilver Salt Photography Book—”), compiled by Nippon Shashin Gakkai (Society of Photographic Science and Technology of Japan), pages 89-117 and 182-201, published by Corona Publishing Co., Ltd. (1982).
In recent years, the diazo compounds have also been applied to recording materials of the type which require fixing images formed therein. Representatives of hitherto proposed recording materials of such a type are light-fixing thermal recording materials in which images are formed by heating diazo compounds and coupler compounds in accordance with image signals and making these compounds react with each other. And the images are fixed by irradiation with light. These recording materials are described in Koji Sato et al., Gazo Denshi Gakkai-shi (Journal of Institute of Image Electronics Engineers of Japan), vol. 11, No. 4, pp. 290-296 (1982).
However, active diazo compounds in such recording materials lose their reactivity even in the dark through gradual decomposition by heat. Therefore, those recording materials have a drawback of being short in shelf life. With the intention of overcoming such a drawback, the method of encapsulating diazo compounds and thereby isolating them from promoters of their decomposition, such as water and bases, was proposed. According to this method, the recording materials can have dramatically improved shelf life. This proposal is described in Tomomasa Usami et al., Gazo Denshi Gakkai-shi (Journal of Institute of Image Electronics Engineers of Japan), vol. 26, No. 2, pp. 115-125 (1987).
On the other hand, the walls of microcapsules having glass transition temperatures higher than room temperature are impervious to substances at room temperature, whereas they become pervious to substances at temperatures higher than glass transition temperatures. Therefore, those microcapsules are thermally responsive ones and suitable for use in thermal recording materials. More specifically, a thermal recording material having a support coated with a thermal recording layer containing thermally responsive microcapsules enclosing a diazo compound, a coupler compound and a base enables (1) improvement in long-term stable storage of the diazo compound, (2) formation of developed color images by heating, and (3) fixation of the images by irradiation with light.
Recent years have seen addition of more functionality, e.g., an ability to form images in multiple colors, to the thermal recording materials as recited above. In keeping with the recent trend toward more functionality, there are growing needs for property enhancements of the recording materials, including enhancement of unprocessed stock storability the recording materials have before recording and enhancement of light fastness the recording materials have in image and non-image portions after recording. These circumstances are described in JP-A-4-135787 and JP-A-4-144784.
Further, JP-A-4-201483 proposes the method of using an acetoacetoanilide compound as a coupler for forming a yellow image. However, the thermal recording material adopting such a method has a drawback of being insufficient in the properties mentioned above.
On the other hand, azolinyl acetic acid derivatives as described in JP-A-63-115891 and J. Chem. Soc. Perkin Trans. 1, pp. 1845-1852 (1987) have never been examined on their suitability as couplers used in the thermal recording materials.